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The Out of Africa Theory proposes that modern humans (Homo sapiens) originated in Africa about 200,000–300,000 years ago and began migrating to other continents around 60,000–80,000 years ago. As they spread across the world, they replaced earlier human species, like Neanderthals and Homo erectus. Fossil and genetic evidence strongly support this theory, showing that all humans today share a common African ancestry. -
The Land Bridge Theory proposes that the first humans entered the Americas from Asia by crossing a landmass called Beringia, which connected Siberia and Alaska during the last Ice Age (about 15,000 to 20,000 years ago). Sea levels were lower then, exposing the land bridge. After crossing, people gradually moved south through an ice-free corridor into the rest of the Americas. -
he Solutrean Hypothesis suggests that the first humans in the Americas came from Europe, not Asia. According to this theory, people from the Solutrean culture (who lived in what is now France and Spain about 20,000 years ago) crossed the Atlantic Ocean along the edge of ice sheets using boats or by walking over ice. -
The Coastal Migration Theory suggests that the first humans to reach the Americas did so by traveling along the Pacific coastline from Asia, rather than through an inland land bridge.